Identifying Dominant Structural and Material Contributors to Enthesis Stress Redistribution Via Cotter’s Method

Abstract

The enthesis is a mechanically graded attachment that distributes load between soft connective tissue and bone across a severe stiffness mismatch without causing catastrophic stress concentration, making it essential for joint function. Although various structural and material features of the enthesis have been studied, their relative importance to stress redistribution remains unclear. This gap limits the design of durable replacements that reproduce enthesis mechanics.  To address this issue, this study applied Cotter’s method within a finite element framework to identify the features that significantly influence stress management.

Two-dimensional finite element models of the enthesis were generated with ligamentous, uncalcified fibrocartilage, calcified fibrocartilage, and subchondral bone regions. Twenty structural and material parameters were varied across relevant ranges, and their influences were ranked using outputs measured at the ligamentous-UFC interface, tidemark, and cement line under tensile, shear, and combined loading. The results revealed that enthesis stress redistribution is governed by a limited but non-minimal subset of features. Amongst the features, the interfacial geometry at ligamentous-UFC interface was especially influential, influencing stress results both locally and distally.

These findings demonstrate that enthesis mechanics depend on coordinated interactions amongst the properties across regions. They provide a quantitative foundation for selecting design elements in enthesis repair and biomaterial replacement techniques. Overall, the study shows that the proposed technique provides a reliable and efficient framework for determining influential parameters in heterogeneous tissue mechanics.